Control device



Jan. 2, 1940. 'w, KUHN 2,185,814

CONTROL DEVICE Filed Feb. 7; 1955 AHTTHTH 451mm Patented Jan. 2, 1940PATENT OFFICE CONTROL DEVICE Clarence W. Kuhn, Milwaukee, Wis., assignorto Cutler-Hammer, Inc., Milwaukee, Wis., a corporation of DelawareApplication February 7 1935, Serial No. 5,364

2 Claims.

This invention relates to control devices for apparatus such as electricrefrigerators, and more particularly to range adjusting mechanisms forsuch devices.

Control devices for electric refrigerators are commonly provided with aloading spring for controlling the cycles of operation of therefrigerator. The loading spring is usually shop adjusted to providepredetermined normal cycles of operation of the refrigerator and is alsousually provided with a range adjusting mechanism to enable the user toeffect modification of such cycles. It is desirable that the rangeadjusting mechanism be operable to modify the cycles of operation so asto provide for operation of the refrigerator at various refrigeratingtemperatures and also at temperatures which are sufficiently high toeffect defrosting. Also in order to facilitate indication of the settingof the range adjusting mechanism it is desirable that the same beprovided with an adjusting knob or lever which is rotatable through anangle of less than 360 degrees to effect all aforementioned temperaturesettings.

Heretofore it has been attempted to effect adjustment of the loadingspring by means of a screw of uniform pitch, but in some instances thedesired range of adjustment could not be obtained by a single revolutionof the control knob without resort to a screw of objectionable pitch,whereas in other instances it is desirable to effect widely varyingdegrees of adjustment of the loading spring by the adjusting knob orlever upon equal degrees of movement of the latter in different parts ofits range.

The present invention has among its objects to provide an improved rangeadjusting mechanism for control devices of the aforesaid character whichprovides for adjustment of the loading spring in a manner to meet theaforementioned requirements.

Another object is to provide a range adjusting mechanism of theaforesaid character which is of simple, rugged and inexpensiveconstruction.

Various other objects and advantages of the invention will hereinafterappear.

The accompanying drawing illustrates an embodime'nt of the inventionwhich will now be described, it being understood that theembodiment'illustrated may be modified in various respects withoutdeparting from the spirit and scope of the appended claims.

In the drawing,

Figure 1 is a. side view of a refrigerator control device embodying theinvention a portion of the enclosing casing being broken away andportions of the operating mechanism being shown in section; I

Fig. 2 is afragmentary sectional view taken substantially on line 22 ofFig. 1;

bracket I 4 fixed within the casing I.

Fig. 3 is a fragmentary front elevational view of the device shown inFig. 1;

Figs. 4 and 5 are detail views of certain of the adjusting parts shownin Fig. l, the parts illustrated in Fig. 5 being shown in section, and

Fig. 6 is a developed view of a cam portion on the adjusting part shownin Fig. 4.

Referring to Fig. l, the invention is shown in connection with arefrigerator control device of the type shown in my copendingapplication Serial No. 708,804, filed=January 29, 1934, but it may beused in connection with control devices of other types. 1

Briefly, the refrigerator control device shown in Fig. 1 includes a boxenclosing casing i having a switch unit 2 and a fluid conditionresponsive device 3 mounted therein. Said switch unit includes aninsulating base 4 which carries a pivoted bridging contact element 5 anda pair of cooperating stationary contacts, one of which is illustratedat 6. Contact element 5 is movable with a snap action into and out ofengagement with its cooperating stationary contacts by an over-centerspring I, said spring being operatively connected to an operating knob 8slidably mounted within an opening in the front wall 9 of casing I. Theswitch unit 2 also has a free tripping overload mechanism associatedtherewith which acts under overload conditions to move contact element 5into open position through the medium of the spring I and which isresettable by the knob 8. However, the overload mechanism need not beconsidered-for the purpose of this application.

The fluid condition responsive device 3 includes a bellows l secured tothe rear wall of easing l and having a communicating pipe extension IIon the rear end thereof. Thepipe ll may be connected to the low pressureside of the refrigerator to provide for operation of the bellows bypressure in that part of the apparatus, or it may contain an expansiblegas and be arranged at a point contiguous to the refrigerating apparatuswhere the temperature and consequently the pressure within the pipe andbellows varies in accordance with operations of the refrigerator.

The front end of bellows Ill bears against a vertically arranged leverl2, pivoted at i3 upon a A coil spring l engages lever l2 to opposeexpansive movements of the bellows l0 and said lever has a snapoperating mechanism associated therewith for moving bridging contact 5into and out of circuit closing position. Such operatingmechanismincludes a lever il pivoted at l8 upon bracket l4 and anover-center spring l8 which is held under compression between the freeends of levers l2 and Il. Movement of lever I1 is limited in onedirection by-insulating base 4. and in an opposite direction by anadjustable stop 20 secured to the rear wall of casing I, and said leveris arranged to operate the movable contact element 5 through the mediumof an insulating bar 2| slidably mounted within a recess in insulatingbase '4.

Upon a decrease in temperature bellows l0 contracts under the action ofthe spring 15 and for a given low temperature value determined by thesetting of spring I5 lever I2 assumes a position wherein the axis ofspring I9 is located to the left of pivot l8, whereupon lever I1 isadapted to move with a snap action into the position shown in Fig. 1 toeffect opening of the bridging contact 5 against the action of spring 1.Upon an increase in temperature bellows 3 expands against the action ofthe spring 16 and for a given high temperature value also determined bythe setting of spring l5, lever l2 assumes a position wherein the axisof spring [9 is located to the right of pivot l8, whereupon lever I'lmoves with a snap action out of the position shown in Fig. 1 intoengagement with the stop 20 to permit reclosure of the contact element 5under the action of spring I. As is apparent, variation of the degree ofcompression of spring 15 causes variation of the temperature values atwhich the contact element 5 is opened and closed, the temperature valuesat which said contact element is opened and closed being raised byincreasing the degree of compression of said spring, and being loweredby decreasing the degree of compression thereof.

Spring I5 is held under compression between lever l2 and a nut 22 whichis adjustably mounted upon an externally threaded sleeve 23. Sleeve 23is slidably mounted upon a rotatable stem 24 and is held againstrotation by an enlarged head 25 which is slotted as shown in Fig. 2 toreceive a horizontally arranged rib projection 23 formed on casing I.Stem 24 is rotatably mounted within an opening in the front wall 9 ofcasing l and is held against forward movement by a shoulder 21 thereonwhich engages a washer 28 bearing against the rear face of said wall.The front end of stem 24 has an adjusting knob 29 secured thereto by ascrew 39 and the rear face of said knob is formed to provide a stop 3|which cooperates with a stop projection 32 on the front face of wall 3to limit rotation of said knob in opposite directions.

The inner end of stem 24 is recessed to provide a cam race 33 forreceiving a pin 33 fixed to sleeve 23. As shown in Fig. 6, cam race 35is shaped to provide spiral portions of different pitch, the portion A-Bof said cam race being of relatively slight. pitch and extending throughan angle of sutstantially 246 degrees, and the portion A.C being ofrelatively steep pitch and extending through an angle of substantially72 degrees.

The aforedescribed range adjusting mechanism is so assembled that whenknob 29 is in position I (Fig. 3) the angular position of stem 24 issuch that pin 33 on'sleeve 23 is located intermediate the cam portionsA-B and A-C, as shown in full lines in Fig. 6. Nut 22 is then shopadjusted upon sleeve 23 to compress spring I5 to such a degree that therefrigerator is started and stopped at selected temperature values toprovide normal cycles of operation thereof.

Upon rotation of knob 23 in a clockwise direction out of position I theportion A-B of cam race 33 acts through the medium of pin 36 to movesleeve 23 outwardly and thereby decrease pin 36 into the dotted lineposition shown in Fig.

6 and sleeve 23 is thus moved inwardly to increase the degree ofcompression of spring l5. By increasing the degree of compression ofspring IS.

the temperature values at which the refrigerator is started and'stoppedare raised. The portion A--C of the cam race is so designed that only arelatively small angular movement of knob 29 is required to compressspring I! to a degree which will cause operation of the refrigerator attemperatures sufficiently high to effect defrosting.

As hereinbefore stated, knob 29 has a stop 3| on the rear face thereofwhich cooperates with a stop projection 32 on the front wall of casing Iand said stops are arranged to limit rotation of said knob in acounterclockwise direction beyond the defrost position shown in Fig. 3and in a clockwise direction beyond position l0 shown in this figure.

In connection with the foregoing it should be noted that the inventionmay be used in connection with control'devices of types other than thatshown in the drawing. Also it is apparent that the cam adjustingmechanism may be modified to provide loading effects other than'thosehereinbefore described.

What I claim as new and desire to secure by Letters Patent is:

1. The combination with a refrigerator control device having a loadingspring associated therewith, of a cam adjusting mechanism for saidspring including a cam element rotatable through a given range andhaving an adjusting knob associated therewith, said cam element having acamsurface of relatively slight pitch which is effective upon rotationof said element through a major part of its range to adjust said springfor cold control of the refrigerator, and also having a cam surface ofrelatively steep pitch which is effective upon rotation of said elementthrough the remainder of its range to adjust said spring for defrostingcontrol of the refrigerator.

2. The combination with 'a refrigerator control device including athermo-responsive switch having a control part movable in response totemperature variations, of a rotatable cam element movable between givenlimits, a cam follower associated with said cam, a spring associatedwith said control part and connected with said cam follower formodifying the action of said switch upon adjustment of said cam element,said cam element having a normal setting adjacent one of its limits andhaving a cam surface of relatively slight pitch which acts upon movementof said cam element towards its opposite limit to effect cold control ofthe refrigerator and also having a cam surface of relatively steep pitchwhich acts upon movement of said cam element into its former limit toeffect defrosting control of the refrigerator.

CLARENCE W. KUHN.

